Process of galvanizing metals



(SpecimensJ T. 'MIDGLEY &-,'W. '13. NYE. PROCESS OF GALVANIZING METALS.

No. 406,365. Patented July 2, I889.

- yaw/d Nv PUEHS. Phnmljthngnpher. Washingkm. DC.

' UNITED STATES PATENT OFFICE.

THOMAS MIDGLEY AND WALTER I). NYE, OF BEAVER. FALLS, PENNSYLVANIA.

PROCESS OF GALVANIZING METALS.

SPECIFICATION forming part of Letters Patent No. 406,365, dated July 2,1889.

Application filed September 2, 1886.

To all whom it may concern.-

Be it kn own that we, THOMAS MIDGLEY and \VALTER B. NYE, citizens of theUnited States, residing; at Beaver Falls, in the county of Beaver andState of Pennsylvania, have invented certain new and useful Improvementsin the Process of GalvanizingMetals ,and wedo hereby declare thefollowing to beafull, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

This invention relates to improvements in galvanizing metals indifferent formssuch as wire, rods, strips,sheets, pipe, &c. There arevarious disadvantages attending the use or process of galvanizingheretofore practiced, either or allof which result in large loss, notonly on account of injury caused to the material itself, but alsobecause of the necessity of frequently repairing or replacing the panwhich contains the bath. In. the first place the quality of the materialis lessened when the zinc is deposited directlyupon it, it being awell-known fact that the efiect of zinc upon iron is to harden and giveit a certain amount of temper, which is a disadvantage where flexibilityis required, as in the case of galvanized wire. It is also well knownthat zinc in a melted state is extremely susceptible to oxidation, andas the bath ordinarily used has a large surface exposed to the air theloss on this account is considerable. There is also a certain percentage of loss occasioned by the chemical action of the acids generallyused upon the zinc bath. Especial loss and disadvantage result in theseold processes from the formation of what are known as dross and stodge,which in large establishments reaches very large proportions, not onlyfrom the expense of renewing the pans, but on account of the frequentstoppage of operations for that purpose.

The object of our invention is to overcome all these disadvantages, andthus produce a better quality of galvanized material by a much moreeconomical process of manufacture.

Our process consists, first, in immersing the material after it has beentreated with acid in the usual manner in a bath of molten lead and thenpassing it through a small body of $e1'ial No. 212,504. lSpecimens.)

melted zinc, which floats upon the surface of the lead, (by reason ofits inferior specific gravity,) being suitably confined to prevent itfrom spreading over the surface of the lead bath. By thus confining thezinc Within a small space upon the surface of the lead any material tobe treated passes first into and through the lead, and thence directlythrough and out of the zinc, from which it receives the coating. By thisarrangement of the apparatus the surface of zinc exposed to the air isvery small and the amount of oxidation correspondingly reduced. Theinjurious effect of the acid upon zinc'is also entirely obviated, sincethey are not brought in contact. Another important advantage arisingfrom the use of this process is that the wire or other material in itspassage through the lead is heated to a temperature nearly, if notquite, up to that of the zinc, and thus the hardening effect of zinc ina molten state upon metal at a normal temperature is entirely prevented.This heating of the material also tends to prevent the formation ofdross, ordinarily caused by the great difference in temperature betweenthe bath and the material exposed to it. By using the small body of zincand restraining it in place by movable partitions the loss resultingfrom the affinity of zinc with the iron of the pan itself is alsocompletely prevented, this action being restricted to the partitionsthemselves, which are easily removed and replaced at any time and at asmall cost.

\Ve have devised an apparatus for carrying out our process, which isillustrated in the accompanying drawings, in which Figure 1 is alongitudinal section on theline 00 0c of Fig. 2. Fig. 2 is a plan view,and Fig. 3 is a cross-section on the line y y of Fig. 2.

A represents the large iron-lined pan, which contains a bath of moltenlead kept in that condition by the application of heat in any suitablemanner, or as hereinafter described.

B represents the zinc bath, which is formed by means of walls D D. Thisbath has an 7 open bottom which permits the lead to enter it to acertain height, as shown. It will be understood that the walls composingthe zinc bath may be located at any point relatively to the pan A, theirposition being governed IOO by the nature and shape of the materialunder treatment. We have shown them in the drawings as supported at theexit end of the lead bath when used for galvanizing wire. \Vithin theseretaining-walls is confined a body of melted zinc, which, by reason ofits smaller specific gravity, floats upon the surface of the lead in thepan A.

E represents the acid bath, and a a designate rollers, by means of whichthe strands b of wire are fed and guided, passing from the acid bathdirectly into and through the molten lead, and being carried thencedirectly through the body of zinc, as shown.

F represents a cover over the zinc bath, and G a chamber, into whichtheproducts of combustion pass from a fire-box H, through cover F, out ofpipe shown in drawings. Passages K extend along the sides of the pan Aand are provided with ash-pits L beneath them. Both pans are thus heatedand theirtemperature maintained at the same point.

Having thus described our invention, what we claim, and Wish to secureby Letters Patent, is as follows:

The above-described process of galvanizing metal, which consists inpassing the metal into and through a large body of lead, and through andout of a smaller body of zinc floating upon the lead, as hereindescribed, and for the purposes set forth.

In testimony whereof we aflix our signatures in presence of twowitnesses.

THOMAS MIDGLEY. WALTER B. NYE. Vitnesses:

JOHN L. GREENHOVV, A. \VoLF.

